Magneto



April 1, 1924. (1,488,975

I P. BROWN MAGNETO Filed April 25 1921 3 Sheets-Sheet 1 lNi/EIOR V M fr7441 ATTORN EYS P. BROWN April 1 1924.

MAGNETO Filed April 25 1921 I5 Sheets-Sheet 3 )QAQ &

INVENTOR WJJ/ZWz W 1 ATTORNEYS April '1, 1924. 1,488,975

%[ Myra ATTORNEYS QBe it known that I, PHELPS Patented Apr. 1, 1924.

UNITED/"STATES. P

'PHELPS BROWN, 0]? SPRINGFIELD, MASSACHUSETTS.

MAGNETO,

Application filed April 25, 1921. Serial No. 464,345.

The whom it may concem: I

BROWN, a citizen of the-United States, residing at Springfield, in thecounty of Hampden and State of Massachusetts, have invented new anduseful Improvements in Magnetos, of which the following is aspecification.

, This invention relates to improvements in magnetos and 'is especiallydirected to magnetos of the type wherein a reciprocating, armature movesinto and out'of engagement with magnetic poles to vary the flux in; amagnetic circuit and by such variationlto cause the eneration ofelectricity in a suitable winding. v

The invention is particularly concerned with mechanismfor actuating thearmature in a novel manner. Heretofore, it has been thought essential,in magnetos of the type described, to apply to the armature verysuddenly, if not practically instantaneously, a relatively high initialforce to dislodge the armature from its poles and overcome the opposingforce due to magnetic attraction, Hence, the use of the'haminer which,when suddenly released, is driven toward the armature and, afteracquiring considerable momentum, engages the latter with an impact whichsets the armature suddenly in motion at high. speed. Such actuation ofthe armature was considered necessary in order to provide'for a rapidchange in flux in the generating-windings. Other prior art magnetos, ofthe type under con,- sideration, while dispensing with the ham- 1 mer,have nevertheless retained the sudden andpractically instantaneousrelease of the armature to allow the sudden application of aconsiderable initial driving force.

The broad object of this invention is to provide, in a magneto ofthetype in which an armature is moved into and out of contact with magneticpoles, driving mechanism arranged to build up on the armature,

while held to its poles, a difi'erential of force to disengage ittherefrom; such differential,-which, by reason of its infinitesimalinitial value. is insufficient to movethe-armature at highspeed,--increasin rapidly as soon as an-air gap is establishe between Ithe armature and poles'and soon becoming effective to so movethearmature by reason of the rapid weakening of the resistance, of whichmagnetic attraction is always an element.

According to this feature of the invention, as soon as the armature isseparated v by the least air gap from its poles, thatopposing force dueto magnetic attraction will be greatly lessened and, as the air gapwidens, will progressively and very rapidly diminish (at the very least,in propor tion to the square of the distance of separation).Accordingly, although only an infinitesimal initial differential offorce existed to move'the armature, such differem tial is rapidlyincreased by the rapid .di-

minution of the force of magnetic attrac- I tion and, after the armaturehas moved a 7 short distance away from 1ts poles, it will acquire asufficiently rapid speed. In order to render this mode of actuation ofthe armature most effective, choke-coils are associated with themagnetic circuit and, at the timethat the armature leaves its poles,these coils are arranged in a closed electrical circuit, which is laterbroken after the ar- I mature has attained the requisite speed. Thepractical effect of this arrangement is to hold the flux in the magneticcircuit until the armature acquires a sufiicient speed and hasintroduced a sufficient reluctance in the magnetic circuit, whereupon anopening I of the choke-coil circuit will result in a desired rapidchange of flux in the generat ing winding.

7 An important advantage of this mode of operation is that it rendersavailable the use of far less violent motions than have heretofore beenemployed for actuating the armature and yet permits sparks of highintensity to be produced independent of engine speed. It eliminates thenecessity for the use of cams which release the follower for a freefall. The principal advantage of This feature of the invention may bemade use of for various purposes, according to the time of the extraopening and closing. Oneway in which this feature may be used toadvantage, is to close the choke-coil circuit, as the armatureapproaches the poles and comes within the influence of magnetic attraction, and to hold the circuit closed until the armature is seated.This results in impeding the establishment of flux in the magneticcircuit and substantially reduces the magnetic attraction effect uponthe armature, which otherwise tends to pull the armature against itspoles rapidly with a sharp and undesired noise. By re-opening thechoke-coil circuit after the armature is engaged with its cores, theflux is allowed to rapidly build up in the magnetic circuit, and afterthe flux has been built up, the circuit is closed, prior todisengagement of the armature, to hold the flux in the magnetic circuituntil the armature has moved far enough away from the poles to attainthe desired speed, whereupon the circuit is opened to permit a rapiddecrease of flux for the generation of current. The advantage ofreducing the effect of magnetic pull, as the armature nears its poles,is thus obtained without the disadvantage of later impeding the rapidbuilding up of the flux by keeping the circuit closed after seating ofthe armature on its poles.

The two features, above set forth, are highly important in a magneto ofthe type described and are each independent of the other, although bothcontribute to quiet operation. As compared with the prior art, lessviolent motions are utilized, which permit operation at much higherspeeds without undue noise and wear on parts. Particularly, as to thefirst feature, the necessary armature speed can be obtained by much moreslowly acting means than have heretofore been used and still sparks ofhigh intensity can be produced at lower motor speeds.

Other objects of the. invention relate to improvements in theconstruction and arrangement of parts and will appear in the followingdescription and in the illustrative embodiment of the invention in theaccompanying drawings, in which,

Fig. 1 is a fragmentary elevational view showing the mounting of themagneto on an engine;

Figs. 2 and 3 are somewhat enlarged front and side elevational viewsrespectively of the magneto;

Fig. l is an enlarged front elevational view of the magneto with thecasings removed to show its interior;

Fig. 5 is a cross-sectional view of the magneto Fig. 6 is an elevationalview showing the group assembly of the moving parts of the magneto;

Fig. 7 is a diagrammatic-a1 view illustrative of the electricalconnections of the magneto;

' neto with the group 0 Fig. 8 is a bottom plan view of the magpartsshown in Fig. 6 removed Figs. 9, 10, 11, and 12 are diagrammatical viewsillustrative of successive steps in the operation of the breaker points,which control the opening and closing of the choke-coil circuit; and

Figs. 9 10, 11, and 12 are diagrammatical views showing the relativepositions of the armature and poles which obtain when the breaker pointsare in the respective position shown in Figs. 9, 10, 11 and 12.

In these drawings, there is shown, in full detail, an embodiment of theinvention incorporating many desirable features relating to theparticular construction and arrangement of various parts, which,although important and preferred, are not essential as far as thebroader aspects of the invention, heretofore outlined, are concerned. Asto each of the latter, the showing is to be taken merely as anillustrative example of one of many suitable types of magnetos, in whichthey may be embodied.

The magneto includes a group of stationary parts, such as the magneticsource, cores, and coils, which may be supported in any suitable manner,as by a bracket a from the engine frame, as b, and a second group ofmovable parts, such as the armature and associated mechanism, which maybe ac tuated from the engine by various means. One illustrative exampleof such means is shown in Fig. 1. Thus. the crankshaft of the engine.indicated at 0, drives the camshaft (Z, as by gearing c, at the desiredratio of speed. The cam-shaft d has mounted thereon a cam 7, which ishere used also to support the group of moving parts. The contour of camf is best shown in Fig. 3 and, as there shown, includes a gradual rise9, a dwell l2. and a drop 1', which is gradual, as compared to the dropof cams heretofore used to permit a free fall and a practicallyinstantaneous descent of the cam-follower. It will be seen, therefore,that the cam will permit a relatively gradual descent of thecam-follower. followed by a rise which usually, although notnecessarily, is considerably more gradual than the descent thereof, andfinally. by a dwell of the cam-follower.

The stationary group of parts includes a back frame 15, from which allthe other parts of this group are supported. This member 15, which is ofnonmagnetic ma terial. is provided with tapped holes 16 to permit. itsattachment to the bracket (1 described and also with aforwardly-extending boss 17. Mounted in and secured to the latter, as bythe screw 18, is a rod 19, which extends downwardly below the lower edgeof the frame and forms a guide for the moving parts of the magneto.

The source of magnetic flux, in this particular instance, comprises aseries of permanent bar magnets arranged. insuperposedrelationand'grou'ped into a unit for convenient assembly in the general. mannerdisclosed in U. S. Letters Patent No. 1,335,119 granted on an inventionof T. G. Louis. That is, the ends of like polarity of all magnets arereceived within substantiall U-shaped cli s 21, to which they are firm yheld, as by s ims or wedges 22. The clips 21, although of magneticmaterial, are not hard, as are the magnets 20, and are readily drilledto receive the attaching devices, later to bedescribed. Various othermeans may be employed for securing the magnets in place and the clipsdescribed are given'merely as an illustration of one of many suitablemeans.

A magnetic pole-piece is provided for each pole of the magnetic'sourceand each of these pole-pieces is made up of two rectangular blocks 23and 24. The two blocks for each pole-piece, as shown in Fig. 5, arearranged side by side and are recessed to receivebetween them the upperend of a core 25." Thelatter, as indicated in Fig. 8, is built up oflaminationswhich are drawn together by, and held to, the'mating pairofblocks by a single screw 26 (Fig. 5). The latter passes through theback frame 15, through the block 24 and core 25 and threads into theblock 23. The screw 26 serves to draw the blocks together, therebyclamping the laminations of core 25 and also securing these parts to theback frame 15. The clips 21, above described, are secured to theirrespective pole-pieces'by screws 27 which pass upwardly through thelatter and thread into the lower part of the clips, there being twoscrews for each clip, as indicated in Fig. 5. The two pole-pieces may befurther tied together'by a bar 28, ofnon-magnetic material, whichconnects the spaced blocks 23 and is secured thereto by screws 29. Thetwo cores 25 extend downwardly from their polerpieces in parallelrelation, one on each sideof the guide-rod 19, and terminate at a shortdistance'below the lower edge of frame 15. Near their lower ends, thelaminations oft-he cores are clamped to gether and connected to theframe 15 in a manner similar to that'above described except that twomembers 30 and 31, of nonmagnetic material, 'suflice for both cores. Twoscrews 32, passing through frame 15, member 30and the'cores 25, threadinto member 31 and serve to draw the members together and hold them tothe frame.

Upon "each core 25, and between the points at which it is clamped, areprovided two coils 33'and 34 arranged one uponthe other. The inner'coils33 are provided fora choking function, either to retard the buildingup,'or the diminution of, magnetic flux in cores 25.. The outer coils 34constitute the generating winding. The electrical connections of thesecoils, are shown in Fig. 7... The coils 34 are usually, although notneces-- sarily, connected in .series, as by a wire 35 joining oneterminal of each coil. The other terminals of the generating winding,constituted by the connected coils, are the service terminals.Customarily, one terminal is grounded, as by a wire 36, to the frame ofthe magneto and the other extends to the ignition system, as indicatedby the wire 37 extending to a spark-plug s.

The two coils 33 are also usually, although not necessarily, connectedin series, as by a Wire 38 joining one terminal of each coil. The otherterminals of the choke-winding, afforded by the connected coils 34, arecon nected to relatively-movable breaker-points 39 and 40 and acondenser 41, is bridged across these terminals in the usual manner.Usually, as shown, one terminal of one coil 33 is connected, as by awire 42, to one side of the condenser and grounded to the frame of themachine, whereby to conveniently connect with the movable breaker-point40, which, as will appear, is in constant metallic connection with. theframe. The correspond- 45, thereby providing for a magnetic circuit ofalternately low and high reluctance through the windings.

.ing terminal of theother coil is connect The armature 45, as best shownin Fig. 5.

may bemade up of laminations in the usual manner, although this'is notnecessarily essential. The armature is fixed to a guide sleeve 46,having a flanged lower end against which the lower face of the armatureabuts, and the laminations are spread apart at the center of thearmature topermit the sleeve to pass t-herethrough. Bolts 47, locatedonopposite sides of sleeve 46, pass through the armature and serve toclamp the laminations thereof together as well as to bind them to thesleeve. Slidable within sleeve 46, and uponthe guide-rod 19, is a secondsleeve 48 having a forked lower end 4.9 which receives I a roll 50 toride upon cam f. Bot-h sleeves 46 and 48 have longitudinal slots 51 and52, respectively, extending from their upper ends downwardly asubstantial distance. These slots function as keyways, both beingarranged to cooperate with a single key 53 in rod 19, which keys permitsthe desired vertical sliding movements of the two sleeves and yet holdsthem in the desired angular relation to keep the armature and rollproperly positioned with respect to cores 2'5 and cam f, respectively.

Preferably, although not necessarily according to all features of theinvention, the armature 45 is not lifted directly by the cam-follower orlifting sleeve 48 but rather through the intermediary of resilientmeans. As shown, such means takes the form of two coil-springs which acttogether to provide the desired strength, although, of course, onespring of the desired strength may equally well be used. These springsare preferably housed within two telescoping. cup-shaped housings 56 and57. The housing 56 loosely slips over the sleeve it and rests upon theshoulder attorded by the intersection'of the fork it) therewith, alsoforming a seat for the spring. The housing 5?, as shown, is slipped oversleeve to previous to its attachment to armature 45 and, after suchattachment. is held between the armature and the flanged end of thesleeve. although obviously it need not be so held. The two housings,even when the springs 50 are fully expanded, overlap and therefore underall conditions enclose the springs and prevent the ingress of dust and.dirt which might otherwise work their way between the two sleeves it;and TS to cause rapid wear on these relatively sliding parts.

The armature is moved away from cores 25 by a driving-spring 58. Thelatter, as shown, a coil spring which encircles the sleeves t6 and andacts between a springscat 59. which abuts the lower face of the boss 17on frame 15. and a cup-shaped spring-seat which slips over sleeve l6 andacts against the upper face of armature .5. As shown, a plate 61. alsoloosclv fitting on sleeve to, is interposed between scat (it) and thearmature and projects laterally therefrom for connection to theinterrupter mechanism to be. later described. As shown in Fig. 8. themembers 30 and 31 are recessed centrally at 62 to receive and closelytit the peripheral wall of the cup-shaped springseat 60, and such wallis of sutl'icient longitudinal extent so that. its open upper end neverpasses out of the lower end of opening 60, thus preventing the ingressof dust and dirt into the magneto through the bottom closure atl'ordedby the members 30 and 3].

The interrupter mechanism includes a cvlindrical casing 63. which isdriven into an opening in the member 31 and thereby held stationarily tothe frame structure already described. This casing extends upwardly inparallelism with the line of travel of the armature and is located atthe front of the magneto for convenient access and inspection. it theupper end of the casing 6 is a bridge 64. in which the stationarybreakerpoint 39 is adjust-ably mounted and from which it is suitablyinsulated, all as indicated in Fig. 4. The movable breaker-point 40 iscarried on the upper end of a relatively long cylinder which closelyfits in and is guided by the casing 63. The lower end of cylinder (35 isclosed except for a central opening, to receive a rod 66 which passesloosely therethrough and into the easing. The upper end of rod 66carries a head 67 and between this head and the closed upper end ofcasing 65 is a spring 68, through the intermediary of which the cylinder65 is lifted from the rod (56. The latter, in its descending movement,lowers cylinder 65 by r ason of the abutment of head 67 with the closedlower end of the cylinder. The lower end of rod 66 is threaded into, andthereby adjustably secured to, the projecting portion of the plate 61above described. screw-driver slot is provided in the lower end of rod(36, whereby it may be conveniently turned for adjustment and a lock-nut(i9 is provided on the rod to prevent change of the adjustment.

5! to he not d that the movable breakerpoint it can yield relatively toits actuating rod Such yield is desirable for several reasons. First.the travel of rod 66 need not be the same as the travel of point 40.

Second. it is desirable that the latter be less than that of rod 66 tocompress the spring 68 after engagement of the points 39 and 40, so thatthe latter will be held firmly pressed together even after considerablewear. Third, it is desired. according to one feature of the invention.to be able to open the breaker-points after they have been closed byupward movement of the armature and while the latter is seated on itscores. For this purpose. a lever 70 is pivoted intermediate its ends at71 to a split collar i2 secured to casing 63 by the clamp lug-screw T2shown in Fig. 4. One end of this lever bears on theupper face ofcylinder (35. and the other end is forked to straddle guide-rod l!) andlie in the path of the sleeve 4 '.his sleeve has a greater travel thanthe armatur. and after the latter has been ed. continues to moveupwardly and in such niovcmeut engages and lifts the inner end of lever7t). thereby depressing its outer end and hiwering cylinder 65 with thelircakeriioint 40 carried thereby. On a reverse n'iovement. the sleeve48 moves downwardly ufiiciently to release lever 70 and allow thebreaker-points to close previons to disengagement of the armature fromits poles.

The time of this extra opening and closing of the breaker-points may bevaried as desired. as by adjusting the collar '72 axially on casing('33. whereby the engagement of lever 70 bv sleeve 48 may be made tooccur earlier or later than above described. \Vhile the describedarrangement. is preferred, in

so far as it permits a substantial reduction of the magnetic ull on theupthrow of the armature, the utility of the extra opening and closing ofthe breaker-points is not confined to this one feature.

For the purpose of preventing ingress of dust and dirt to the guidecylinder 63, its otherwise open lower end is closed b a dust-cap 73,which fits over rod 66 an is held in place by a spring 74 acting betweencap 7 3 s and plate 61.

The lubrication of the various moving parts of the magneto iseffected'in the following manner. A plug 75 of felt, or othersuitable'ma-terial, is inserted in the lower end of sleeve 48 andarranged to bear on roll 50. The working face of cam fis lubricated andsome of this lubricant is picked up by roll 50 and transferred to theplug .75, which absorbs it. On each reciprocation of the armature, thesleeve 48 and rod 19, having a relative movement, function like a pumpand draw up the lubricant from plug 75 and squeeze it out between theirengagin surfaces, which are thereby lubricate Such lubricant eventuallyleaves b way of the upper end of sleeve 48 and alls onto the outersurface thereof, upon which sleeve 46 slides, thereby lubricatingthesesliding surfaces. The latter action is assisted by the pumping actiondue to the telescoping casings 56 and 57.

The lubrication of the interrupter mechanism is, effected by one or morerin of felt 77, or like absorbent material, whic are placed on rod 66and pickup oil supplied into casing 63 through a passage 76, which atits outer end is yielda ly closed b the usual closure, indicatedconventional y at 7.8 The felt rings 77 distribute the oil over thelower portion of the inner surface ofcasing 63, from which it is workedupwardly by the sliding guide cylinder 65.

The housing of the magneto comprises a plurality of bent or pressedsections of nonmagnetic material, {which completely enclose all partsabove the bottom cilosure members 30 and 31, and prevent the ingress ofdust and dirt as well as protecting the parts from mechanical injury.The outer contour of theassembled units, comprising parts 15, 30 and 31,shown in Fig. 8, is the same as that of the assembled unit comprisingparts 15, 23, 24 and 28, and the space between these two units is closedby side casings shaped to conform to such contour.

As shown, one side casing section 78 en compasses the back, both ends,and overlaps the ends of, the front of the magneto and isheld in placeby screws79 threading into the units just described. This leaves anopening in front, through .whichaccess may behad to the interruptermeclranism, such opening being closed by a second casing section80similarly held in place by screws 81.

The magnet assembly is encased by a top casing section 82 which overlapsthe upper portions of the side casings and is secured in place by someof the screws79 and 81 used to hold the latter.

The particular details of the construction and arrangement of parts, asabove set forth, are especially advantageous from the point of view ofquantity production manufacture. The entire magneto is subdivided intounits, the parts of each of which may be separately assembled, and thenthe assembled units mounted in their proper working relation with oneanother by simple means. The frame, pole-pieces, cores, and associatedparts constitute one unit to which prior to complete assembly, areapplied the coils 33 and 34 previously made up as another unit to slipover the cores 25. The magnets 20 are separately assembled in theirclips 21 as a distinct unit and are readily appliedto the frame unit bythe screws 27. The armature, and all its associated reciprocatory parts,constitute another unit which is applied in correct working relation tothe other units by simply slipping the sleeves 46 and 18 over theguide-rod 19, the key 53 by its engagement n slots 51 and 52 positioningthese parts in proper angular relation, as above set forth. The armatureunit is held in place by the roll 50 resting on cam f. Associated withthe armature unit is a unit consisting of the reciprocable parts of theinterrupter mechanism, and thisunit requires merely to be slipped inplace in casing 63, which is previously applied to member 31 during theassembly of the frame unit. All the reciprocating parts of the .magnetoare readily applied or removed by the one simple operation of pushingorpulling the sleeve 48 over or from the guide-rod. This assembly ofreciprocating parts is clearly shown in Fig. 6 and the only operationconnected with the assembly of these parts, requiring any appreciableamount of time, is the assembly of the l aminations of the armature andthe clamping of them to sleeve 46, to which the spring-housing '57 ispreviously applied. Thereafter, the housing 56 is slipped in place onsleeve 48 and the springs 55 dropped over the latter, after which sleeve48 is inserted in sleeve 46. The plate 61, carrying all thereciprocating parts of the interrupter mechanism, is then slipped oversleeve 48, followed by seat 60. and spring 58, which completes theassembly.

The operation of the magneto, and more especially the movements of thearmature. with which the broad features of the invention are concerned,will now be described; Assuming that the cam-follower is positioned onthe low point of cam fand that the latter is rotating in the directionof the arrow (Fig. 3), the cam-follower will be gradually raised by theportion 9 of cam The raising of the armature, however, is preferably notdirectly accomplished there by for it is usually desired to seat thearmature upon the magnetic poles (comprising the lower ends of cores asgently and as quietly as possible. Therefore, the camfollower transmitsits lifting force to armature through the intermediary of the spring orsprings Opposing the action of the latter is the drive-spring 58, andthe armature is thus carried upward between two forces, which naturallyseek a balance. The upward movement of the armature is therefore notdirectly proportional to the movement of the cam-follower for the latterencounters increasing resistance as it moves upwardly by the compressionof spring 58, and as the latter compresses the spring must compress tobalance it. Therefore, the upward movement of the armature, which may beinitially nearly as fast as the cam-follower, soon becomes slower andslower as it approaches the poles. This particular mode of lifting thearmature, although desirable and preferred because it permits a. gentleseating of the armature on its poles, is not essential to the broadfeatures of the invention.

In the above description of the forces acting on armature -15 during itsupward t avel no consideration was "iron to the upward force which wouldnormally tend to draw the armature to its poles with a sharp noise. foras the armature nears the latter the magnetic pull would ordinarilyincrease very rapidly, and this rapidly-increasing forceadded to that ofspring 56 would tend to defeat the object sought for, viz, thedepositing of the armature on the cores as quietly as possible. However,the effect of magnetic pull is substantially reduced so as to be apractically negligible factor in the described operation. This isaccomplished by the closing of the choke-coil circuit during the latterpart of the upward flight of the armature. The breaker-points,controlling the opening and closing of this choke-coil cir cuit, are,when the armature is in its lowest position (Fig. 9), open as shown inFig. 9. As the armature nears its poles to a position such, for example,as is indicated in Fig. 10, it has moved sulticiently to carry thebreaker-point it) into engagement with the fixed breaker-point 39, thusclosing the circuit in which the choke-coils are located. On continuedmovement of the armature, spring" compresses to take care of theovertravel of rod 66. and the points remain closed until after thearmature has been seated on its poles. These coils, when in av closedelectrical circuit, oppose a change of flux in the magnetic circuit, andin this instance they oppose the building up of the flux in cores 25 andconsequently there will not be immediately a magnetic pull on the armature of anything like the usual strength. The force, due to magneticpull, is substantially reduced over that which would otherwise exist ifthe choke-coil circuit were left open.

After the armature has been seated on its poles, the mun-followercontinues its upward travel, the spring 55 by its further compression,permitting this action. This overtravel of the cam-follower is importantsince it insures that the armature will continue to be seated on itspoles even after extended wear. It is also important as it affords ameans for opening the breakerpoints after the armature has come to reston its poles and is no longer available to actuate them. Continuedtravel of the camfollower opens the breaker-points as illustratcd inFig. 2, thus allowing the flux to build up rapidly in the now closedmagnetic circuit and the follower may, as shown. dwell in its upperposition for an interval to insure this result, although such dwell isnot necessarily essential.

As the cam-follower rides onto the portion 27 of the cam f, thesupporting forces acting on arl'naturc 45 are progressively diminished.In addition to the supporting force of spring there is now a substantialforce of magnetic attraction acting in conjunction with it, whichadditional force is, until the armature leaves its poles, substantiallyconstant. The first result is a progressive, instead of aninstantaneous, expansion of spring and a lowering of sleeve 48,unaccompanied by any movement of armature 4-5. Thus, the breaker-pointsare closed before the armature leaves its poles, the relative positionsof these elements being shown in Figs. 1]. and 11. Thus, the choke-coilsare again brought into play on the magnetic circuit, but for adifi'erent purpose, viz, to oppose any sudden change in magnetic fluxwhen the armature leaves its poles.

The disengagement of the armature from its poles is not accomplished bythe sudden application of a substantial initial force. ()n the contrary,when in the descent of the cam-follower. the force opposing the drivingaction of spring 58,in this instance that due to spring 55 and that dueto magnetic attraction,become just slightly less than that of spring 58,the armature will begin to move but naturally slowly in its initialinfinitesimal step of downward movement because the driving force isinfinitesimal. Practically, spring 55 becomes almost entirely releasedbefore the armature begins to move, and the major force left to opposespring is that due to magnetic attraction. The instant, however, thatthe least air gap created between the armature and its poles, thisopposing force is very much diminished and on doubling the air gap thisforce is at least quartered, and so on. Thus, once the armature isstarted fromits poles, no matter how slowly, by the very smallestdifferential of force, its subsequent movement is rapidly accelerated onaccount of the exceedingly rapid diminution of the resisting force. Thepractical result is that a high armature speed is obtained after thearmature has moved away from its poles a certain distance, and at thepoint of maximum speed,'or as nearly thereto as it can be arranged, thebreaker-points open. The choking effect on the magnetic circuit, havingbeen thus done away with, there results a very rapid change of flux inthis circuit, thereby inducing a high voltage in the generating winding.Thus, by the expedient of the breaker-points and choke-coil winding,which may be likened to a valve for controlling the flux in the magneticcircuit, it is possible to hold the flux in the latter until thearmature gets under way and attains a sufficient speed. Otherwise,'thechange in flux would be relatively gradual because it would dependentirely on the speed of the armature in the initial stages of itsdownward flight;

To complete the description of operation, it should be noted that thespring 55 has still another function which is to yieldingly and quietlyarrest the armature in its downward flight. After the breaker-pointshave opened for the purpose of releasing the flux in the magneticcircuit, the driving force of spring 58, byits expansion, weakens and inaddition encounters increasing opposition by reason of spring 55 and theforces due to these two elements seek and find their balance and thusarrest the armature in the desired quiet manner.

While in the foregoing description the driving spring 58 has beenconsidered as stronger than the force due to magnetic attraction, underthe conditions illustrated in Fig. 5, it is not necessarily essential tothe success of this mode of actuating the armature, for it is simplynecessary to supply the deficiency in force necessary to unseat thearmature by other means and the unseating, once accomplished, theinitially insuflicient force of the driving spring be comes sufficient,due to the rapidly waning influence of magnetic pull. Moreover, un dersuch conditions, of course, magnetic attraction may be utilized tomaintain the armature seated,once it is deposited on its poles, andconsequently the supporting springs 55 are not necessarily essential tothe success of the mode of actuating the armature in its downwardflight.

The closing of the breakeroints and the holdingof them closed until t 1earmature is seated, while important and preferred for the reasonsoutlined, are obviously not concerned in any way with the downwardflight of the armature. Even on the upward flight of the armature, thetiming of the extra closing and opening may be changed as oocasionrequires to effect other results. For example, if the rise 9 of cam f isso abrupt as to move the armature rapidly enough to cause an upthrowspark, the closing of the choke-coil circuit will tend to kill thisspark, even if this opening and closing are not timed exactly asdescribed.

In conclusion, it may be pointed out that the necessary speed of thearmature is really obtained by fully utilizing the factor of the rapidlydiminishing force of magnetic pull by the creation and the increase ofan air gap. This factor may be termed magnetic retraction asdistinguished from magnetic attraction and is the factor relied uponhere to obtain armature speed, as distinguished from the hammer blow orthe substantial, and instantaneously applied, initial force heretoforeused to produce an initial high speed. Inasmuch as the flux can be heldby the choke-coils for an interval sufficient to accelerate the armatureto the desired speed, initial speed becomes unnecessary.

Although the invention has been described here with considerableparticularity in order to make clear to those skilled in the art apreferred meansof making use of it, it is to be understood that theinvention is not limited to the details illustrated and described exceptas they are included in the following claims.

What I claim is- 1. In a magneto, of the type wherein an armature isperiodically moved into position to complete a magnetic circuit entirelythrough magnetic material, means including the force of magneticattraction for exerting a force tending to hold the armature in saidposition, means for exerting a force tending to move the armature awayfrom said position, and means for progressively changing the relation ofthe opposing forces acting on the latter until a differential of forceis created for the purpose of moving the armature away from saidposition, such differential of force increasing rapidly as the armaturemoves away from said position due to the rapid diminishing of theopposing force of magnetic attraction by the creation of an air gap insaid circuit.

2. In a magneto, of the type wherein an armature is periodicallymoved'into position to complete a magnetic circuit entirely throughmagnetic material and is subsequently moved out of said position to varythe reluctance of said circuit and a generating winding is associatedwith said circuit in which currents are induced by the variation of fluxtherein; resilient means progressively brought into action andcooperating with the rapidly diminishing resisting force of magneticattraction to produce a rapid movement of the armature away from saidposition, a closed circuit chokewinding associated with the magneticcircuit, and means for openim the choke winding circuit after thearmature has moved away from said position.

3. In a magneto, of the type wherein magnetic members are connected tothe poles of a magnetic source and an armature moves into and out ofengagement with said members to connect and disconnect the same and varythe reluctance of the magnetic circuit and a generating winding isassociated with said circuit in which currents are induced by thevariation of flux therein; driving means tending to move the armatureaway from said members but periodically exerting a force less than thetotal of opposing forces, means acting relatively gradually to changethe relation of the opposing forces until a differential of force existsto start the armature away from said members, such differential becomingrapidly greater aiter dlsengagement of the armature by the creation ofan air gap between it and said members. whereby the opposing force ofmagnetic pull is rapidly weakened.

-l. In a magneto, of the type wherein an armature moves into engagementwith mag netic poles to complete a magnetic circuit entirely throughmagnetic material and subsequently moves out of such engagement to varythe reluctance of said circuit and a generating winding is associatedwith said circuit in which currents are induced by the variation of fluxtherein; mechanism for disengaging the armature and moving it away fromits poles against the opposing force of magnetic attraction, said mechanism including means for exerting upon the armature a force whichincreases progressively from zero until the opposing force is overcome.whereby the armature at the inslant of leaving its poles moves slowlyunder a dill'erential or" force, the latter by reason ot the rapidlydiminishing opposing force of magnetic attraction being etl'ective tomove the armature at rapidly increasing speed. a closed circuit.choke-winding associated with the magnetic circuit, and means to opensaid winding after the armature has moved away from the polessuliiciently to acquire the requisite speed.

In a magneto, of the type wherein an arnniture moves into engagementwith magnetic poles to complete a magnetic circuit en tirely throughmagnetic material and subsequently moves out of such engagement to varythe reluctance of said circuit and a generating winding is associatedwith said circuit in which currents are incuced by the variation of fluxtherein; mechanism for disengaging the armature and moving it away fromits poles against the opposing force of magnetic attraction, saidmechanism including means for building up a force until it justoverbalances the opposing forces, whereby the armature will move awayfrom its poles slowly under a small initial force and the latter, due tothe rapidly diminishing resistance of the opposing force of magneticattraction 011 separation of the armature from its poles, becomeseilective to move the armature at rapidly increasing speed, and achoking winding associated with the magnetic circuit to hold the fluxtherein until the armature has moved away from its poles sufficiently toacquire the requisite speed.

c. In a magneto, oi. the type wherein magnetic members are connected tothe poles of a magnetic source to act as cores and pole pieces and anarmature is moved into and out of contact with said members to conmetand disconnect the same, means for depositing the armature on saidmembers, driving means arranged to act on the armature in opposition tothe force of magnetic attraction, said first-named means arranged towithdraw relatively gradually from the armature and until the drivingmeans can move the armature.

7. In a magneto, of the type wherein an armature is moved into and outof contact with magnetic poles, means including the force of magneticattraction between the poles and armature for exerting a force tendingto hold the latter to the former, means for exerting a force tending tomove the armature away from its poles, and means adapted to be drivenfrom the engine in definite timed relation therewith and periodicallyeffective to gradually change the relation of the opposing forces untilthat exerted by the second named means becomes just sufiicient tooverpower that exerted by the first named means and start the armatureaway from its poles, whereby as the armature continues to move theinitially small difi'erential of force effective to move it increasesrapidly due to the rapid din'iinishing of the opposing force of magneticattraction.

8. In a magneto, of the type wherein an armature moves into engagementwith magnetic poles to complete a magnetic circuit entirely throughmagnetic material and subsequently moves out of such engagement to varythe reluctance of said circuit and a generating winding is associatedwith said circuit in which currents are induced by the variation of fluxtherein: driving means tending to move the armature a ay from its poles,means for gradually diminishing the forces opposing said means until thelatter become effective to start the armature from its poles, thearmature rapidly increasing in speed after separation from its poles dueto the rapid diminution in the opposing force of magnetic attraction,and a choking winding associated with the magnetic circuit to hold. theflux therein until the armature has attained the desired speed.

9. In a magneto, of the type wherein an armature moves into engagementwith magnetic poles to complete a magnetic circuit entireiy throughmagnetic material and subsequently moves out of such engagement to varythe reluctance of said circuit and a generating winding is associatedwith said circuit in which currents are induced by the variation of fluxtherein; mechanism for moving the armature, including compressibledevices acting in opposition thereon, and means for compressing saiddevices until one overbalances the other and the armature is moved intoengagement with its poles, and later progressively releasing saiddevices until the second just overbalances the combined force due to thefirst device and magnetic attraction, whereby the armature at theinstant of leaving its poles moves at a slow rate which is rapidlyincreased due to the rapidly diminishing force of magnetic attraction,and a choking winding associated with the magnetic circuit to hold theflux therein until the armature has moved away from it poles asuflic-ient distance to acquire the requisite speed.

10. In a magneto, of the type wherein an armature moves into and out ofconnecting engagement with magnetic members connected to the poles of amagnetic source to vary the reluctance of a magnetic circuit and agenerating winding is associated with said circuit in which currents areinduced by the variation of flux therein; resilient means arranged toact in opposition on said armature, and actuating means transmitting itsforce through one ot said resilient means for moving the armature intoengagement with said members, said means arranged to progressivelyrelease one of said resilient means until the other is enabled todisengage the armature from said members.

11. In a magneto, of the type wherein an armature moves into and out ofengagement with magnetic poles to vary the reluctance of a magneticcircuit and a generating winding is associated with said circuit inwhich currents are induced by the variation of flux therein; achoke-winding associated with the magnetic circuit and arranged in anelectric circuit which can be opened and closed, and means for closingsaid electric circuit before the armature engages its poles and forlater opening it after the armature has engaged said poles.

12. In a magneto, of the type wherein an armature moves into and out ofengagement with magnetic poles to vary the reluctance of a magneticcircuit and a generating winding is associated with said circuit inwhich currents are induced bv the variation of flux therein; achoke-winding associated with the magnetic circuit and arranged in anelectric circuit which can be opened and closed, and means for closingsaid electric circuit before the armature engages its poles and torlater opening it after the armature has engaged said poles and againclosing it before the armature leaves its poles.

1?). In a magneto, ot. the type wherein an armature move into and out ofengagement with magnetic poles to vary the reluctance of a magneticcircuit and generating and choking windings are associated with saidcircuit; an electrical circuit including the choking winding, and meansfor closing, opening, again closing, and again opening said electricalcircuit on each reciprocation of the armature.

14:. In a magneto, ot the type wherein an armature moves in a straightline path toward and away 'from magnetic poles secured to a frame, aguide sleeve passing through the armature, a driving sleeve telescopingwithin the first sleeve and having a shoulder, a spring encompassing thedriving sleeve and acting between said shoulder and one side of thearmature, a guide-rod mounted in the frame to slidingly receive thedriving sleeve, and a spring encompassing the guide sleeve and actingbetween the opposite face of the arn'iature and said frame.

15. In a magneto, of the type wherein an armature moves in a strai htline path toward and away from magnetic poles secured to a frame, aguide sleeve passing through and secured to the armature, a drivingleeve telescoping within the first sleeve and having a shoulder, aspring encompassing the driving sleeve and acting between said shoulderand one side of the armature, a guide-rod mounted in the frame toslidingly receive the driving sleeve, a key in said guide-rod, slotsprovided in said sleeves in which said hey engages, and a springencompassing the guide sleeve and acting between the opposite face ofthe armature and said frame.

16. In a magneto, of the type wherein an armature moves in a straightline path toward and away from magnetic poles secured to a frame, aguide sleeve passing through the armature, a driving sleeve telescopingwithin the first sleeve and having a shoulder, a spring encompassing thedriving sleeve and acting between said shoulder and one side of thearmature, telescoping cup-shaped members to enclose said spring andarranged one on each of said sleeves, a guide-rod mounted in the frameto slidingly receive the driving sleeve, and a spring encompassing theguide sleeve and acting between the opposite face of the armature andsaid frame.

"ne t -o a ranle including es extending hctween Jers, coils on saidcores, a source 1c flux superposed on one of said 18. in a magne flux,cores connect d therewith, COllS on the cores, means enc ing saidsource, coils and cores crvccpt for snor extensions of the latter whichpass through and closely tit one wall of said encasing means, an ogeuingprovided in said wall hetwcen he cores, an armature to periodicallyconnect aid c1:- tensions of the cores, and reciprocati mechanismassociated with the armature and including parts movahle through saidopen ing, and a member carried by sai; mecha nism to closelv tit andclose saio opening at tri vel of the an turc.

all times during the na 19. In a niagnett, of the type in which an:triaatn 1* moves into and out of engagement with magnetic poles to varythe reluctance of a magnetic circuit and generating and CllOliingwindings are as ociated with said circuit: interrupter mechanismincluding an element movable to open or close the choking winding,mechanism tor actuating the armature including a part having a travelgreater than the latter, means movable h v the armature for moving saidelement, and means inovahle by said part t'or actuating said element ina direction opposite to that in which it is actuated hy the arn'laturewhen moving in the same direction as said part.

20. In a magneto, of the type in which an armature moves into and out ofengagement with magnetic poles to vary the reluctance of a magneticcircuit and generating and choking windings are associated with saidciraiit, cooperating and relativelv-movable breaker-points to controlthe choking winding. actuating mechanism for the armature including amember movable in the same direction as the, a mature but having agreater range of travel, means movahle l v the armature on one strokefor moving the mo 'ahle breaker-point in one tlll'fititifll'l, and mainsmovable by aid memher on the same stroke for moving the movablellt'QzilJQF-POlllt in an opposite direction after it has ceased to hemoved by the armature.

ill. in a magneto, ot the type in waich an armature moves into and outof engagement vith magnetic poles to varv the reluctance of a magneticcircuit and generating and chokwindings are asso iated i said circuit,cooperating an d relativelr-movahle breaker-points to control thecholtingwiuding, actuating mechanism for the armature including anuanher mova in the same direction as the armature hut having a greaterrange of ,HYQl. means movz hie hy the armature on one stroke {or movingthe movable breaker-point in one direction, means mow ahl in: saidnieinher on the same stroke for 11.; the mrnrahle hr alcn-point in anopdirection after i has ceased to he novcd by the ature. and vieldahlemeans through which one 5 said means transmits its force to the movaulel;realtei'-11ioiiit.

22. In a magneto, having a magnetic source, cores, and a generatingwinding together with a casing enclosing them except for one end of eachcore. a rcciprocahle armature to periodiaillv connect the cores at saidend, actuating mechanism for the armature including reciln'ocatingtr-arts as- C X e vi ,d with the latter. tln- 1 rniaturc and all satpart capable of being withdrawn without opening the casing.

523. In a magneto, having a magnetic source, cor s, 'enerating andchoking windings and interrupter merhanism associated with the chokingwinding and including ielativcl v movahlc hrealtci points, a casing toenclose all said clen'icnts except for one end oi each core, areeiprocahle armature to periorrlicall v connect the cores at said end,actuating mechanism for the armature including reciprocating partsassociated with the latte the mundane. movable breakerpoiut and all said1 arts capable of being withdrawn without opening the casing.

In testimony whereot I have afiixed my signature.

PHELPS ltitOlVN.

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